Hand-held portable lawn trimmers for cutting and trimming vegetation are well known. Such devices may be of the gas or electric motor type, with the gas motor type typically comprising a compact internal combustion motor mounted at one end of an elongated hollow tubular frame member or tubing which carries at its opposite end a cutting tool operatively connected to the motor by means of a drive shaft received within the tubing. A handle is mounted to the tubing at its motor end along with motor control means, such as a trigger switch, for convenient manual manipulation and control of the tool. The electrical motor type is similarly configured except that for lightweight models the electric motor may be mounted adjacent the cutter end with electrical wiring running through the tubing from the handle.
Such devices are commonly referred to as "lawn trimmers." Heavy duty versions are usually of the gas motor type so that they can be used almost anywhere that an operator can walk, without limitation of an electrical cord length restriction. Such versions are often supported by a harness worn by the user that clips to a ring in the vicinity of the handle.
The cutting tool is usually a cutting head having one or more flexible strings as of monofilament nylon line disposed on a rotating drum, operatively connected through a gear drive to the drive shaft and fastened by a securing means to the elongated frame member. On electric trimmers, the cutting head may be attached directly to the output shaft of a motor that is mounted at the lower end of the machine. Such a head operates to "whip" the contacted vegetation with the spinning monofilament line to break the same off rather than actually cutting it.
On some trimmers, the monofilament head is replaceable with a circular metal or hard plastic rotary cutting blade useful for cutting tall, tough weeds and small shrubs. It is also known to replace the head with a reciprocating cutting blade, such as shown in FIG. 1b of U.S. Pat. No. 4,122,601, for use in pruning soft trees like palm and fruit trees. The '601 patent shows a trimmer with a multisectioned tubular frame member of sufficient length to provide a reach of approximately 2 meters in order to facilitate the pruning of tall trees.
In addition to being known to substitute rotary and reciprocating cutter blades for a monofilament head, it is also known to convert conventional lawn trimmers into devices that perform noncutting functions by replacing the head with a conversion attachment. For example, U.S. Pat. No. 4,242,794 describes a blower attachment for converting the trimmer into a blower for removing leaves and grass clippings from sidewalks or other surfaces. U.S. Pat. No. 4,501,332, and page 41 of the Lawn, Garden & Power Equipment Owner's Manual, published by Technical Publications, Intertec Publishing Corporation, Overland Park, Kans. disclose attachments for converting such apparatus into various earth cultivating devices. And, a conversion device is also known for converting a conventional trimmer into a screw propeller boat propulsion device, as described in U.S. Pat. No. 4,752,256.